Packaging machinery for packaging food products such as cheese and meat, particularly, processed meat, such as bacon, are known in the art. In general, packaging machinery which are cam-operated are designed such that the rotating camshaft imparts rotational, horizontal and/or vertical motion to various camshaft components, i.e., cams, gears, sprockets and the like. These camshaft components, in turn, drive the various mechanical operations needed to produce a packaged food product.
One type of cam-operated food packaging machine is a rotary die wheel packaging machine. Rotary die wheel packaging machines are designed to automatically perform multiple packaging operations around a central rotating die wheel. In this machine, package forming/sealing, food loading and package dispensing operations are synchronized with and take place around a central rotating die wheel to make the finished packaged food product. In operation, a first packaging film is loaded into forming/sealing die cavities located on the central rotating die wheel. Each forming/sealing die cavity includes a peripheral edge called a die bead where hermetic seals are formed around the package. After the film is received, a film tucker assembly forces the film under film clamps where film is secured to the die, where it is then heated to a predetermined temperature to soften the film. A vacuum is applied from the backside of the die cavity facing the softened film and the film is thermoformed into the shape of the die cavity. As the die wheel advances, a food item is transferred from a loading station onto a second packaging film. The food item is then carried into the die cavity where it is sandwiched between the first and second packaging films. Next, the outer peripheral edges which extend beyond the food item are joined together during a first heat sealing operation. The seal that is formed extends around the outer peripheral edges of the die cavity or die bead and includes at least one aperture or unsealed area between the first and second packaging films. As the die wheel advances further, a chamber comes in contact with the die where the atmosphere surrounding the food item and between the packaging films is evacuated through the aperture. A second heat sealing operation is then performed to close the aperture and hermetically seal the food item within. Finally, the film between the die cavities is cut and a product picking station removes each individual package from the die wheel.
In general, rotary die wheel packaging machines are designed so that, during normal operation, the die wheel rotates is one direction, i.e., clockwise or counter-clockwise, so that each packaging operation may be synchronized to the forward direction of rotation of the die wheel. However, when power is removed to these machines, particularly after an emergency shut-down, the die wheel may respond by moving for short distances in the opposite direction. This can result in damage to mechanical components and assemblies operationally interconnected to the die wheel. For example, if the die wheel rotates backwards, the film tucker can damage the die beads by scratching or marring the surface of the die bead. A damaged die bead surface will not allow hermetic seals to be formed in the food package and, therefore, adversely affect the quality of the finished package.